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diff --git a/src/rwmutex_test.cpp b/src/rwmutex_test.cpp
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+++ b/src/rwmutex_test.cpp
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+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "rwmutex.h"
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+#include <array>
+#include <thread>
+#include <vector>
+
+namespace {
+constexpr const size_t NumThreads = 8;
+}
+
+// Check that WLock behaves like regular mutex.
+TEST(RWMutex, WLock) {
+  dap::RWMutex rwmutex;
+  int counter = 0;
+
+  std::vector<std::thread> threads;
+  for (size_t i = 0; i < NumThreads; i++) {
+    threads.emplace_back([&] {
+      for (int j = 0; j < 1000; j++) {
+        dap::WLock lock(rwmutex);
+        counter++;
+        EXPECT_EQ(counter, 1);
+        counter--;
+      }
+    });
+  }
+
+  for (auto& thread : threads) {
+    thread.join();
+  }
+
+  EXPECT_EQ(counter, 0);
+}
+
+TEST(RWMutex, NoRLockWithWLock) {
+  dap::RWMutex rwmutex;
+
+  std::vector<std::thread> threads;
+  std::array<int, NumThreads> counters = {};
+
+  {  // With WLock held...
+    dap::WLock wlock(rwmutex);
+
+    for (size_t i = 0; i < counters.size(); i++) {
+      int* counter = &counters[i];
+      threads.emplace_back([&rwmutex, counter] {
+        dap::RLock lock(rwmutex);
+        for (int j = 0; j < 1000; j++) {
+          (*counter)++;
+        }
+      });
+    }
+
+    // RLocks should block
+    for (int counter : counters) {
+      EXPECT_EQ(counter, 0);
+    }
+  }
+
+  for (auto& thread : threads) {
+    thread.join();
+  }
+
+  for (int counter : counters) {
+    EXPECT_EQ(counter, 1000);
+  }
+}
+
+TEST(RWMutex, NoWLockWithRLock) {
+  dap::RWMutex rwmutex;
+
+  std::vector<std::thread> threads;
+  size_t counter = 0;
+
+  {  // With RLocks held...
+    dap::RLock rlockA(rwmutex);
+    dap::RLock rlockB(rwmutex);
+    dap::RLock rlockC(rwmutex);
+
+    for (size_t i = 0; i < NumThreads; i++) {
+      threads.emplace_back(std::thread([&] {
+        dap::WLock lock(rwmutex);
+        counter++;
+      }));
+    }
+
+    // ... WLocks should block
+    EXPECT_EQ(counter, 0U);
+  }
+
+  for (auto& thread : threads) {
+    thread.join();
+  }
+
+  EXPECT_EQ(counter, NumThreads);
+}